perfmonctl


SYNOPSIS
       #include <syscall.h>
       #include <perfmon.h>

       long perfmonctl(int fd, int cmd, void *arg, int narg);
       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION
       The  IA-64-specific  perfmonctl()  system call provides an interface to
       the PMU (performance monitoring unit).  The PMU consists of  PMD  (per-
       formance  monitoring  data)  registers  and PMC (performance monitoring
       control) registers, which gather hardware statistics.

       perfmonctl() applies the operation cmd to the input arguments specified
       by  arg.   The number of arguments is defined by narg.  The fd argument
       specifies the perfmon context to operate on.

       Supported values for cmd are:

       PFM_CREATE_CONTEXT
              perfmonctl(int fd, PFM_CREATE_CONTEXT, pfarg_context_t *ctxt, 1);
              Set up a context.

              The fd parameter is ignored.  A new perfmon context  is  created
              as  specified  in  ctxt  and  its file descriptor is returned in
              ctxt->ctx_fd.

              The file descriptor can be used in  subsequent  calls  to  perf-
              monctl()  and  can  be  used  to  read event notifications (type
              pfm_msg_t) using read(2).  The file descriptor is pollable using
              select(2), poll(2), and epoll(7).

              The  context  can  be  destroyed by calling close(2) on the file
              descriptor.

       PFM_WRITE_PMCS
              perfmonctl(int fd, PFM_WRITE_PMCS, pfarg_reg_t *pmcs, n);
              Set PMC registers.

       PFM_WRITE_PMDS
              perfmonctl(int fd, PFM_WRITE_PMDS, pfarg_reg_t *pmds, n);
              Set PMD registers.

       PFM_READ_PMDS
              perfmonctl(int fd, PFM_READ_PMDS, pfarg_reg_t *pmds, n);
              Read PMD registers.

       PFM_START
              perfmonctl(int fd, PFM_START, NULL, 0);
              Start monitoring.

       PFM_STOP
              perfmonctl(int fd, PFM_STOP, NULL, 0);
              Restart monitoring after receiving an overflow notification.

       PFM_GET_FEATURES
              perfmonctl(int fd, PFM_GET_FEARURES, pfarg_features_t *arg, 1);

       PFM_DEBUG
              perfmonctl(int fd, PFM_DEBUG, val, 0);
              If val is nonzero, enable debugging mode, otherwise disable.

       PFM_GET_PMC_RESET_VAL
              perfmonctl(int fd, PFM_GET_PMC_RESET_VAL, pfarg_reg_t * req, n);
              Reset PMC registers to default values.

RETURN VALUE
       performctl() returns zero when the operation is successful.  On  error,
       -1 is returned and errno is set to indicate the cause of the error.

VERSIONS
       perfmonctl() is available since Linux 2.4.

CONFORMING TO
       perfmonctl()  is  Linux  specific  and  is  available only on the IA-64
       architecture.

NOTES
       Glibc does not provide a wrapper for this system call;  call  it  using
       syscall(2).

SEE ALSO
       gprof(1)

       The perfmon2 interface specification

COLOPHON
       This  page  is  part of release 3.54 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.



Linux                             2013-02-13                     PERFMONCTL(2)
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